Fermented milk fortified with Kolliphor HS 15 stabilized selenium nanoparticles modulates gut microbiota and improves selenium bioavailability in vivo.

Selenium (Se) deficiency affects over 1 billion people worldwide, leading to increased susceptibility to various diseases and impaired gut health. To address this issue, the study aimed to develop a fermented milk (FM) fortified with Se nanoparticles (SeNPs) stabilized with Kolliphor HS 15 (KHS15). The research synthesized and characterized SeNPs-KHS15, showing favourable physicochemical properties with SeNPs sizes of 16 nm and high stability across various pHs (1.81-11.98). Fortified FM exhibited enhanced antioxidant activity and minimal physicochemical changes. In vivo studies revealed significantly improved Se bioavailability, with blood Se levels in rats reaching 2.8 μg/L after 21 days of consumption. The fortified FM demonstrated protective effects on intestinal health in broiler chickens with antibiotic-associated dysbiosis, evidenced by increased villi area in duodenum (1.79-fold) and cecum (4.0-fold). Selective-media plate counts, which are presumptive and were not confirmed by molecular methods, were higher for Bifidobacterium spp. and Lactobacillus spp. and lower for opportunistic taxa in the FM-Se group; these microbiota observations are preliminary. Thus, the developed FM fortified with SeNPs-KHS15 shows promise as a proof-of-concept functional food platform for addressing Se deficiency and modulating gut health, with potential applications in animal and human nutrition pending replacement of the pharmaceutical-grade KHS15 stabilizer with a food-grade alternative. At the same time, the advantage of KHS15 over Tween 80 or other food-grade emulsifiers was not tested.